Conductive coating liquid composition, and an antistatic film and a display device using the same

ABSTRACT

Provided is a display device having an antistatic film made of a conductive coating liquid composition. The conductive coating liquid composition includes 10 to 100 parts by weight of a silane sol based on 100 parts by weight of a carbon nanotube dispersion liquid composition, and 0.1 to 5 wt % of a polar solvent based on 100 wt % of the conductive coating liquid composition.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No.10-2015-0191574 filed on Dec. 31, 2015, which is incorporated herein byreference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

Technical Field

The present disclosure relates to a conductive coating liquidcomposition, and an antistatic film and a display device using the same.

Discussion of Related Art

With the current rapid development of the information-oriented society,there is a growing need of flat panel displays having excellentcharacteristics, such as slim profile, light weight, and low powerconsumption. Of these, liquid crystal displays have been widely appliedto laptops or desktop monitors due to their excellent resolution, colordisplay, and picture quality.

In general, a liquid crystal display is a device in which two substrateseach having electrodes on one surface thereof are disposed such that theelectrode-formed surfaces face each other, a liquid crystal material isinterposed between the two substrates, and then a voltage is applied tothe electrodes formed on the respective substrates to generate anelectric field, which moves liquid crystal molecules to vary thetransmittance of light, thereby displaying images. Here, much staticelectricity may be generated during the unit processes of manufacturingeach substrate of the liquid crystal display.

In order to discharge such static electricity and effectively releasecharges accumulated at the time of producing finished products,indium-tin-oxide (ITO) or indium zinc oxide (IZO), which is atransparent conductive material, is utilized for an antistatic film onan external surface of the upper substrate. However, indium tin oxide(ITO) and indium zinc oxide (IZO) are very expensive transparentconductive metal materials, which thus increase the manufacturing costs.Especially, the price of indium, a rare metal, which is the main rawmaterial of indium tin oxide (TIO) and indium zinc oxide (IZO), hasincreased rapidly in recent years, and its supply is currentlyrestricted due to the export control policy of the resource holdingcountries.

The recent introduction of portable products with embedded touchsensors, such as mobile phones, PDAs, laptops, etc., which can beoperated by touching the screen, are attracting a lot of attention fromusers. In line with this trend, many attempts have been made in recentyears to add touch functionality to liquid crystal displays that areused as display devices in a variety of applications. Of these, thedemand for in-cell liquid crystal displays with embedded touchfunctionality is on the rise. In-cell liquid crystal displays haveadvantages, such as slim profile, improved cost structure owing to thereduction in the cost of raw materials, and lightweight, since touchelectrodes are formed inside the display panel, without a separate touchpanel attached on the liquid crystal display.

However, in spite of the touch sensors provided inside the display panelwith in-cell technology, static electricity is discharged by theaforementioned antistatic film, and thus the touch sensors are not ableto detect a change in capacitance when touched by a finger or the like,thereby resulting in deterioration in the touch sensitivity of the touchsensors. In other words, the antistatic film serves as a conductor withrelatively high electrical conductivity when compared with an amount ofcapacitance generated by a finger touch or the like, thereby dischargingthe capacitance so that the touch sensors are not able to recognizetouch from a user's finger or the like.

Eliminating the antistatic film to address this problem will lead to ahigher failure rate due to static electricity generated duringmanufacturing, which, in turn, increases the cost of failure and againincreases the manufacturing costs, thus degrading low display quality.

SUMMARY

An aspect of the present invention is to provide a conductive coatingliquid composition which can improve the dispersion of carbon nanotubes.

Another aspect of the present invention is to provide a display devicehaving an antistatic film made of the above conductive coating liquidcomposition.

Yet another aspect of the present invention is to provide an antistaticfilm and a display device which can avoid failures caused by staticelectricity, prevent degradation in touch sensitivity, improve surfaceresistance uniformity, thermal resistance, and reliability, and reducemanufacturing costs by easily discharging static electricity generatedduring the manufacturing process.

One exemplary embodiment of the present disclosure is directed toconductive coating liquid composition comprising 10 to 100 parts byweight of a silane sol and 0.1 to 5 wt % of a polar solvent based on 100wt % of the conductive coating liquid composition.

In another exemplary embodiment, the polar solvent has a polarity of 10or higher.

In another exemplary embodiment, the polar solvent comprises at leastone selected from n-methyl pyrolidone (NMP), dimethyl sulphoxide (DMSO),and dimethyl formamide (DMF).

In another exemplary embodiment, the carbon nanotube dispersion liquidcomposition further comprises 0.05 to 20 wt % of carbon nanotubes, 0.02to 40 wt % of a polyacrylic acid resin, and 50 to 99.93 wt % of astraight-chain alkanol having 2 to 5 carbon atoms based on 100 wt % ofthe conductive coating liquid composition.

In another exemplary embodiment, the silane sol comprises analkoxysilane compound, an acid catalyst, an alcohol-based solvent, andwater.

In another exemplary embodiment, the silane sol comprises 20 to 60 wt %of the alkoxysilane compound, 10 to 70 wt % of the alcohol-basedsolvent, and 5 to 60 wt % of water based on the total weight of thesilane sol.

Another exemplary embodiment of present disclosure is directed to adisplay device comprising an antistatic film comprising the conductivecoating liquid composition described herein.

Another exemplary embodiment of the present disclosure is directed to adisplay device comprising: a display panel on a lower polarizer; anupper polarizer on the display panel; and an antistatic film between anupper substrate of the display panel and the upper polarizer, whereinthe antistatic film comprises carbon nanotubes and a silane sol, andwherein the antistatic film has a sheet resistance of 10⁴ Ω/sq to 10⁹Ω/sq.

In another exemplary embodiment, the display panel further comprisestouch electrodes.

In other exemplary embodiment, the touch electrodes are positioned in anupper or lower part of the display panel.

In another exemplary embodiment, the carbon nanotubes have a sheetresistance of 1,000 Ω/sq to 20,000 Ω/sq.

Another exemplary embodiment of the present disclosure provides anantistatic film comprising carbon nanotubes and a silane sol, whereinthe antistatic film has a sheet resistance of 10⁴ Ω/sq to 10⁹ Ω/sq.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in, and constitute apart of, the present disclose, illustrate various exemplary embodimentsof the present disclosure and, together with the description herein,serve to explain the principles of the invention. In the drawings:

FIG. 1 is a cross-sectional view of a related art display device;

FIG. 2 is a cross-sectional view of a display device according to anexemplary embodiment of the present disclosure;

FIG. 3 is a front view of the display device illustrated in FIG. 2;

FIG. 4 is a plan view of an antistatic film according to an exemplaryembodiment of the present invention, showing the exemplary compositionof the carbon nanotubes and matrix material thereof;

FIG. 5 is a graph showing the sheet resistance of an antistatic film andthe sheet resistance of carbon nanotubes according to an exemplaryembodiment of the present disclosure;

FIG. 6 is a graph showing the sheet resistance of the antistatic filmversus carbon nanotube content according to an exemplary embodiment ofthe present disclosure;

FIG. 7A is a graph showing changes in the sheet resistance of a typicalantistatic film over time, and FIG. 7B is a graph showing changes in thesheet resistance of an antistatic film according to an exemplaryembodiment in high-temperature, high-humidity environments;

FIG. 8 is a graph comparing the percentage by weight of a related artantistatic film over temperature and the percentage by weight of anantistatic film over temperature according to an exemplary embodiment;

FIGS. 9 and 10 are exemplary illustrations of the dispersion of carbonnanotubes;

FIGS. 11 and 12 are schematic illustrations of a display deviceaccording to an exemplary embodiment of the present disclosure;

FIG. 13 is a waveform of a common voltage (Vcom) and touch drivingsignal (TDrv) applied to the touch sensors (Cs) of the display deviceillustrated in FIG. 11;

FIG. 14 is a cross-sectional view of a display panel according to anexemplary view of the present disclosure; and

FIGS. 15 to 17 are schematic illustrations of various display devices towhich an antistatic film of the present disclosure may be applied.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings. Likereference numerals designate substantially like elements throughout thespecification. In the following description, detailed descriptions ofwell-known functions or configurations associated with the presentinvention will be omitted if they are deemed to unnecessarily obscurethe subject matters of the present invention. The names of the elementsused in the following description may be selected for ease of writingthe specification, and may be different from the names of parts inactual products.

FIG. 1 is a cross-sectional view of a related art display device.

Referring to FIG. 1, a display device 100 comprises a lower substrate120, an upper substrate 140 opposite the lower substrate 120, and anantistatic film 150 positioned on the upper substrate 140. A lowerpolarizer 110 a is positioned on an outer surface (bottom in thefigure), a cell 130 is positioned between the lower substrate 120 andthe upper substrate 130, and touch electrodes TE may be disposed withinthe cell 130. Meanwhile, an upper polarizer 110 b is positioned on theupper substrate 140, and the antistatic film 150 is positioned on theupper polarizer 110 b.

The display device 100 of FIG. 1 is an in-cell type display device 100in which the touch electrodes TE are positioned within the cell 130.However, this is merely an example for convenience of explanation. Forexample, the cell 130 may be a liquid crystal layer, and the displaydevice 100 may be a liquid crystal display.

Meanwhile, the antistatic film 150 may be made of indium tin oxide (ITO)or indium zinc oxide (IZO), which are transparent conductive materials,or may be made of a conductive polymer, for example, PEDOT:PSS(polyethylenedioxythiphen:polystyrene sulfonic acid). However, indiumtin oxide (TIO) and indium zinc oxide (IZO) are very expensive metals,which is a factor for the rise in manufacturing costs. Especially, theprice of indium, a rare metal, which is the main raw material of indiumtin oxide (TIO) and indium zinc oxide (IZO), has increased rapidly inrecent years, and its supply is currently restricted due to the exportcontrol policy of the resource holding countries. Moreover, since indiumtin oxide (TIO) and indium zinc oxide (IZO) have relatively low sheetresistance and high electrical conductivity, a capacitance generatedwith the touch of a finger or the like is discharged by the antistaticfilm 150, and therefore the touch sensors are not able to detect touch.Further, the antistatic film 150, if made of a material like PEDOT:PSS,may bring a deterioration in reliability under high-temperature orhigh-humidity environments.

Meanwhile, the antistatic film 150 is connected to the edge of the lowersubstrate 120 via a first conductive member 170 a, a conductiveconnecting member 172, and a second conductive member 170 b. Althoughnot shown, ground pads, etc. made of a conductive material may bepositioned on the edge of the lower substrate 120. Static electricitygenerated in the display device 100 is discharged because of theconductive materials of the first conductive member 170 a, conductiveconnecting member 172, second conductive member 170 b, and lowersubstrate 120.

The first conductive member 170 a and the second conductive member 170 bmay be made of a metal material, e.g., silver (Ag), and the conductiveconnecting member 170 also may be made of a metal material. However,when forming the first conductive member 170 a, the conductiveconnecting member 172, and the second conductive member 170 separately,the number of processes increases and this increases the manufacturingcosts.

Hereinafter, an antistatic film and a display device comprising the sameaccording to exemplary embodiments of the present invention to bedescribed below can solve the above-described problems.

Now, exemplary embodiments of the present invention will be described indetail with reference to the accompanying drawings.

First Exemplary Embodiment

FIG. 2 is a cross-sectional view of a display device according to anexemplary embodiment of the present invention. FIG. 3 is a front view ofthe display device of FIG. 2. FIG. 4 is a plane view of an antistaticfilm according to an exemplary embodiment of the present invention.

Referring to FIGS. 2 to 4, a display device 200 comprises a displaypanel 205 positioned on a lower polarizer 210 a, an upper polarizer 210b positioned on the display panel 205, and an antistatic film 250disposed between the upper substrate 240 of the display panel 205 andthe upper polarizer 210 b.

More specifically, the display panel 205 comprises a lower substrate220, a cell 230, and an upper substrate 240, which are sequentiallystacked. Here, the lower substrate 220 may be an array substrate 220where transistors for driving the cell 230 and various kinds of signallines and electrodes are formed, and the upper substrate 240 may be acolor filter substrate 240 where color filters (not shown) and a blackmatrix (not shown) are formed. In this specification, the lowersubstrate 220 may refer to the array substrate 220, and the uppersubstrate 240 may refer to the color filter substrate 240. The lowersubstrate 220 and the upper substrate 240 may be made of glass, forexample, but are not limited to it.

The display panel 205 may be a liquid crystal panel 205 comprising aliquid crystal layer, and the display device 200 may be a liquid crystaldisplay 200. While this specification mainly describes the liquidcrystal display 200, the present invention is not limited to it. Forexample, the cell 230 may be an organic layer of an organiclight-emitting display. In cases where the display device 200 is aliquid crystal display 200, liquid crystals may be included in the cell230. Thus, an electric field generated by applying a voltage to theelectrodes on the substrates 220 and 240 causes the liquid crystals tomove and therefore the transmittance of light changes, thus allowing theliquid crystal display 200 to display images.

Touch electrodes may be formed in the cell 230. As described above, thedisplay device 200 may be an in-cell type display device 200, andtherefore touch electrodes TE for touch functionality—for example, Rxand Tx electrodes—are embedded in the cell 230. The in-cell touch typeliquid crystal display 200 has advantages, such as slim profile,improved cost structure owing to the reduction in the cost of rawmaterials, and lightweight, since touch electrodes are formed inside thedisplay panel, without a separate touch panel attached on the liquidcrystal display. For example, although not shown, a structure forimplementing touch functionality may be an in-plane switching (IPS)mode, but is not limited to it.

The lower polarizer 210 a and the upper polarizer 210 b perform afunction of polarizing light and emitting it out of the liquid crystaldisplay 200. However, static electricity may be generated when the lowerpolarizer 210 a and the upper polarizer 210 b are attached to thedisplay panel 205. Moreover, static electricity may be generated whendriving the liquid crystal display 200 for displaying images.

The antistatic film 250 is disposed to eliminate such staticelectricity. The antistatic film 250 comprises a matrix material 252 andcarbon nanotubes (CNT) 254 dispersed in the matrix material 252, and theantistatic film 250 may have a sheet resistance of 10⁴ Ω/sq to 10⁹ Ω/sq.More preferably, the antistatic film 250 may have a sheet resistance of10⁷ Ω/sq to 10⁹ Ω/sq. More specifically, the antistatic film 250 may beformed by curing a solution comprising the matrix material 252, thecarbon nanotubes 254 dispersed in the matrix material 252, a dispersedadditive, etc. The antistatic film 250 can improve thermal resistanceand reliability by comprising the carbon nanotubes 254 dispersed in thematrix material 252. A more detailed description of the composition ofthe antistatic film 250 will be given later.

The carbon nanotubes 254 dispersed across the entire surface of theantistatic film 250 exhibit very high hardness and strength in terms ofstructure because they are composed of SP² bonds between carbon atoms.Especially, single-walled carbon nanotubes (SWCNT) may be used as ahigh-strength/ultralight composite material since they have a Young'smodulus of 5.5 TPa and a tensile strength of up to 45 GPa.

The carbon nanotubes 254 may have a sheet resistance of 1,000 Ω/sq to20,000 Ω/sq. As for the in-cell touch type liquid crystal display 200,if the antistatic film 250 has an excessively low sheet resistance(below 10⁴ Ω/sq), a capacitance generated with the touch of a finger orthe like is discharged by the antistatic film 150, and therefore thetouch sensors are not able to detect touch. As such, there is a need toincrease the sheet resistance of the antistatic film 250 and thus toincrease the sheet resistance of the carbon nanotubes 254 to a range of1,000 Ω/sq to 20,000 Ω/sq.

If the carbon nanotubes 254 have a sheet resistance of below 1,000 Ω/sq,the sheet resistance of the antistatic film 250 becomes lower, which mayresult in degradation in touch sensitivity due to discharge. Bycontrast, if the carbon nanotubes 254 have a sheet resistance of above20,000 Ω/sq, the sheet resistance of the antistatic film 250 becomes toohigher, which may result in a reduction in the discharge effect.

The content of carbon nanotubes 254 in the antistatic film 250 may beadjusted depending on a design value of light transmittance. Since thelight transmittance of the antistatic film 250 decreases as the contentof carbon nanotubes 254 increases, the content may be adjusted accordingto the light transmittance required for the product.

Meanwhile, the antistatic film 250 may have a uniform sheet resistanceacross the entire surface—specifically, 10⁴ Ω/sq to 10⁹ Ω/sq, andpreferably, 10⁷ Ω/sq to 10⁹ Ω/sq. As for the in-cell touch type liquidcrystal display 200, if the antistatic film 250 has an excessively lowsheet resistance (below 10⁴ Ω/sq), a capacitance generated with thetouch of a finger or the like is discharged by the antistatic film 150,and therefore the touch sensors are not able to detect touch. As such,the antistatic film 250 requires relatively high resistance. Bycontrast, if the antistatic film 250 has an excessively high sheetresistance (above 10⁹ Ω/sq), this provides superior touch sensitivitybut slows down the discharge of static electricity, thus reducing thedischarge effect.

Accordingly, the antistatic film 250 of the display device 200 accordingto the exemplary embodiment of the present invention requires a sheetresistance of 10⁴ Ω/sq to 10⁹ Ω/sq, and this allows the display device200 to discharge static electricity, thereby avoiding failures caused bystatic electricity and preventing degradation in touch sensitivity.

Meanwhile, one end of the antistatic film 250 is connected to the edgeof the lower substrate 220 of the display panel 205 via the conductivemember 270. Here, the conductive member 270 joins the antistatic film250 and metal pads (or ground pads; not shown) of the lower substrate220 of the display panel 205. Specifically, the conductive member 270serves as a passage to release static electricity out of the device bycovering the edge of the outer surface of the antistatic film 250 andmaking contact with the metal pads (not shown) via a connecting portion270′. The conductive member 270 may be made of a metal material such asgold, silver, or copper, for example.

As compared to the first conductive member 170 a, conductive connectingmember 172, and second conductive member 170 b of the typical displaydevice 200 shown in FIG. 1, the conductive member 270 alone can performthe function of releasing static electricity. This can reduce the numberof processes and shorten the processing time, leading to reducedmanufacturing costs.

However, it should be noted that the shape, arrangement, etc. of theconductive member 270 of the display device 200 shown in FIGS. 2 and 3are for illustration only and the embodiments are not limited to them.

First Experimental Example

The effects of an exemplary embodiment of the present invention will bedescribed below with reference to the attached tables and graphs.

FIG. 5 is a graph showing the sheet resistance of an antistatic filmrelative to the sheet resistance of carbon nanotubes according to anexemplary embodiment of the present disclosure.

As shown in Table 1 below, as the sheet resistance of the antistaticfilm was increased from 477 Ω/sq to 1,800 Ω/sq, the sheet resistanceuniformity of the antistatic film increased from 17.32% to 6.67%. Inother words, this means that the differences in sheet resistance betweeneach region of the antistatic film were reduced.

TABLE 1 Sheet resistance Sheet resistance Hardness Sample (Ω/▭) Unif.(%) of CNT (Ω/▭) (H) 1 10^(7.4)~10^(10.5) 17.32 477 8 210^(7.7)~10^(10.1) 12 .22 1420 8 3 10^(7.7)~10^(9.1 ) 8.33 1466 8 410^(7.7)~10^(8.8 ) 6.67 1800 8

As described above, in order for an in-cell liquid crystal display toperform discharge while at the same time maintaining touch sensitivity,the antistatic film requires a sheet resistance range of 10⁷ Ω/sq to 10⁹Ω/sq.

However, Sample 1 has a sheet resistance range of 10^(7.4) Ω/sq to10^(10.5) Ω/sq, with a large difference between the highest and lowestsheet resistance values, and Sample 2 also has a sheet resistance rangeof 10^(7.7) Ω/sq to 10^(10.1) Ω/sq, with a large difference between thehighest and lowest sheet resistance values. Thus, the sheet resistanceof Samples 1 and 2 differ greatly from region to region, and theirdischarge ability is degraded in regions where the sheet resistance isexcessively high.

On the other hand, as in the case of Sample 4, if the carbon nanotubeshave a sheet resistance of 1,800 Ω/sq, Sample 4 has a sheet resistanceof 10^(7.7) Ω/sq to 10^(8.8) Ω/sq, which allows for performing dischargewhile at the same time maintaining touch sensitivity.

The graph of the sheet resistance uniformity of the antistatic film isdepicted in FIG. 5B. This graph shows that, as the sample number goes upfrom Sample 1 to Sample 4, the sheet resistance of the carbon nanotubesincreases and therefore the sheet resistance uniformity is improved.

FIG. 6 is a graph showing the sheet resistance of the antistatic filmversus carbon nanotube content according to an exemplary embodiment ofthe present invention.

Referring to FIG. 6, a first line L1 represents the sheet resistance ofthe antistatic film of a typical liquid crystal display, and a secondline L2 represents the sheet resistance of the antistatic film of adisplay device according to an exemplary embodiment. Also, the displaydevice of FIG. 6 is an in-cell liquid crystal display.

The first line L1 in Region A has a very steep slope when the antistaticfilm has a sheet resistance of around 10⁸ Ω/sq that allows forperforming discharge while at the same time maintaining touchsensitivity. This means that the sheet resistance of the antistatic filmmay change to a great extent even with a slight change in the carbonnanotube content. In other words, this means that the sheet resistanceuniformity is relatively low.

The second line L2 in Region B has a very gentle slope when theantistatic film has a sheet resistance of around 10⁸ Ω/sq. This meansthat the sheet resistance changes only slightly because the sheetresistance uniformity is relatively high, even with a change in thecarbon nanotube content. Accordingly, the display device according tothe exemplary embodiment can perform an antistatic function while at thesame time maintaining touch sensitivity, even with a change in thecarbon nanotube content.

Table 2 shows the light transmittance relative to the content and sheetresistance of carbon nanotubes according to an exemplary embodiment.

Referring to Table 2, this table shows the content and sheet resistanceof carbon nanotubes according to a design value of light transmittance.Specifically, a display device that requires a light transmittance of100% may be designed such that the carbon nanotube content is 0.13% andthe carbon nanotubes have a sheet resistance of 1,800 Ω/sq. Also, adisplay device that requires a light transmittance of 99% or above maybe designed such that the carbon nanotube content is 0.26% and thecarbon nanotubes have a sheet resistance of 5,000 Ω/sq.

TABLE 2 Transmittance CNT content Sheet resistance Hardness Sample (%)(%) of CNT (Ω/▭) (H) 5 100 0.13 1500 8 H 6 100 0.13 1800 8 H 7 99.5 0.265000 8 H 8 99.4 0.26 7000 8 H 9 98.7 0.26 10000 8 H 10 98.5 0.26 19000 8H

As can be seen from Table 2, it is found that the light transmittancecan be adjusted by adjusting the content and sheet resistance of carbonnanotubes, as long as the antistatic film has a sheet resistance thatallows for performing discharge while at the same time maintaining touchsensitivity.

FIG. 7A is a graph showing changes in the sheet resistance of a typicalantistatic film over time, and FIG. 7B is a graph showing changes in thesheet resistance of an antistatic film according to an exemplaryembodiment in high-temperature, high-humidity environments.

FIG. 7A shows changes in the sheet resistance of an antistatic film madeof a conductive polymer called PEDOT:PSS over time in a 95° C.environment. This graph shows a continuous increase in sheet resistanceover time. Specifically, this graph reveals that the sheet resistancerose up to 9.7 Ω/sq when the initial sheet resistance was set toapproximately 8.5 Ω/sq, and the sheet resistance rose up to 9.2 Ω/sqwhen the initial sheet resistance was set to approximately 8.0 Ω/sq.

On the other hand, referring to FIG. 7B, it was found that theantistatic film according to the exemplary embodiment showed almost nochange in sheet resistance when the antistatic film had an initial sheetresistance of around 8.0 Ω/sq and was exposed to 105° C. for 1,500hours. Similar results were obtained when the antistatic film wasexposed to a high-humidity environment.

Accordingly, it is concluded that the antistatic film according to theexemplary embodiment has better thermal resistance and reliability thanthe typical antistatic film.

FIG. 8 is a graph showing a comparison between the percentage by weightof a typical antistatic film over temperature and the percentage byweight of an antistatic film over temperature according to an exemplaryembodiment.

Referring to FIG. 8, this graph shows the results of analyzing thetypical antistatic film and the antistatic film according to theexemplary embodiment by a thermogravimetric analyzer (TGA). Thethermogravimetric analyzer is an instrument that measures changes in themass of samples by heating the samples.

It was observed that, in the case of the antistatic film of the typicalliquid crystal display, the PEDOT:PSS, a conductive polymer, comprisedin the antistatic film was all lost due to heat at a temperature ofapproximately 500° C. By contrast, it was observed that, in the case ofthe antistatic film of the antistatic film of the display deviceaccording to the exemplary embodiment, the carbon nanotubes were notlost but left up to approximately 900° C.

Accordingly, it is concluded that the antistatic film according to theexemplary embodiment has better thermal resistance and reliability thanthe typical antistatic film.

To sum up, a liquid crystal display with touch functionality can avoidfailures caused by static electricity, prevent degradation in touchsensitivity, improve sheet resistance uniformity, thermal resistance,and reliability, and reduce manufacturing costs by easily dischargingstatic electricity generated during the manufacturing process by meansof an antistatic film 250 with a sheet resistance of 10⁷ Ω/sq to 10⁹Ω/sq uniformly across the entire surface.

Second Exemplary Embodiment

Now, a description will be given of a carbon nanotube dispersion liquidcomposition and a conductive coating liquid composition comprising thesame, which are used to manufacture the above-described antistatic filmaccording to the first exemplary embodiment of the present invention.

FIGS. 9 and 10 are pattern diagrams of examples of dispersion of carbonnanotubes.

The present invention relates to a carbon nanotube dispersion liquidcomposition and a conductive coating liquid composition comprising thesame, and more particularly, to a carbon nanotube dispersion liquidcomposition and a conductive coating liquid composition comprising thesame which can remarkably improve the dispersibility of carbon nanotubesand their stability after dispersion by comprising carbon nanotubes,polyacrylic acid resin, and a straight-chain alkanol with 2 to 5 carbonatoms, and which form a coating film with excellent chemical stabilityand electrical conductivity that is used in the conductive coatingliquid composition, along with a silane sol and improve the uniformityof the formed coating film.

<Carbon Nanotube Dispersion Liquid Composition>

The carbon nanotube dispersion liquid composition according to thepresent invention comprises carbon nanotubes, polyacrylic acid resin,and a straight-chain alkanol with 2 to 5 carbon atoms.

Carbon Nanotubes

Carbon nanotubes are a material with excellent electrical conductivity.A coating film made of carbon nanotubes can be used as conductivelayers, antistatic films, etc. in electronics such as display devicesowing to their excellent electrical conductivity and mechanicalstrength.

The carbon nanotubes (CNT) may be produced by typical techniques,including arc discharge, laser deposition, plasma chemical vapordeposition, vapor synthesis, and pyrolysis, and then thermally treated.Along with carbon nanotubes, carbon impurities such as amorphous carbonor crystalline graphite particles, and catalytic transition-metalparticles are present in products of the above synthesis methods. Forinstance, in the case of arc discharge, 15 to 30 wt % of carbonnanotubes, 45 to 70 wt % of carbon impurities, and 5 to 25 wt % ofcatalytic transition-metal particles are comprised in 100 wt % of theproduct. The use of carbon nanotubes comprising such impurities withoutpurification will deteriorate the dispersibility and coatability of animpregnating solution and make it difficult properly exhibit the uniquephysical properties of carbon nanotubes. Accordingly, the presentinvention uses carbon nanotubes which have as many impurities removed aspossible by thermally treating the product of arc discharge.

Specifically, the product obtained by the above synthesis method is madeinto a sheet or granules having an average diameter of 2 to 5 mm andthen fed into a rotary reactor that is inclined downwards at 1 to 5°with respect to the direction of forward movement (horizontal), and thenoxidized gas is supplied to 1 g of the fed product at 200 to 500 cc/minwhile heating the rotary reactor at 350 to 500° C., followed by thermaltreatment for 60 to 150 minutes. In this case, as the inclined rotaryreactor rotates at 5 to 20 rpm, the product is dispersed to thusmaximize the area of surface contact, and at the same time, the productis moved automatically in the direction of forward movement to thusmaximize the area of surface contact with the oxidized gas and thenthermally treated while preventing local oxidation. By this method, theweight of the fed product can be reduced by 60 to 85%, thereby obtaininghigh-purity carbon nanotubes.

The carbon nanotubes may contain 40 wt % or less of carbon impurities,more preferably, 25 wt % or less of carbon impurities, based on 100 wt %of the carbon nanotubes, in order to ensure dispersion, stability, andelectrical conductivity.

The carbon nanotubes may be single-walled carbon nanotubes,double-walled carbon nanotubes, or multi-walled carbon nanotubes, andthese carbon nanotubes may be used alone, or two or more kinds of themmay be used in combination. Single-walled carbon nanotubes are morepreferable in terms of improvement in interactions with other componentsto be described later.

The content of carbon nanotubes according to the present invention isnot specifically limited, but may be, for example, 0.05 to 20 wt % ofthe total weight of the dispersion liquid composition; preferably, 0.1to 10 wt %; more preferably, 0.1 to 1 wt %. Within this range, thecarbon nanotubes may exhibit high dispersibility, and a coating filmmade of these carbon nanotubes ensures electrical conductivity, scratchresistance, and transmittance.

Polyacrylic Acid Resin

A polyacrylic acid resin according to the present invention is acomponent that acts as a dispersant for effectively dispersing carbonnanotubes. The polyacrylic acid resin dissolves easily in a particulardispersant to be described later, and may bind readily to carbonnanotubes, which are hydrophobic. Moreover, the polyacrylic acid resinmay improve the dispersibility of carbon nanotubes and preventreaggregation through electrostatic repulsion between carbon nanotubestrands and through steric hindrance using the unique properties ofpolymer chains.

The content of polyacrylic acid resin according to the present inventionis not specifically limited, but may be, for example, 0.02 to 40 wt % ofthe total weight of the dispersion liquid composition; preferably, 0.05to 10 wt %; more preferably, 0.1 to 1 wt %. Within this range, thepolyacrylic acid resin is dissolved to an appropriate extent within thecomposition, thereby remarkably improving its activity in dispersingcarbon nanotubes.

The weight-average molecular weight of the polyacrylic acid resinaccording to the present invention is not specifically limited, but mayrange, for example, from 2,000 to 3,000,000; preferably, from 8,000 to12,000. Within this range, the polyacrylic acid resin may easilypermeate between carbon nanotube strands and provide a steric hindranceeffect suitable for reaggregation. Moreover, the polyacrylic acid resinmay exist in a well-dissolved state in the dispersant within thedispersion liquid composition, thereby effectively dispersing the carbonnanotubes.

The dispersion liquid composition of this invention may contain a verysmall amount of water. Hence, the polyacrylic acid resin may becomprised in the dispersion liquid, dissolved or emulsified in water,but the present invention is not limited to this.

Straight-Chain Alkanol with 2 to 5 Carbon Atoms

A straight-chain alkanol with 2 to 5 carbon atoms according to thepresent invention is a dispersion medium for effectively dispersingcarbon nanotubes. Also, it is a hydrophilic alcohol-based solvent thatcan remarkably improve the dispersion stability of carbon nanotubes byinteractions with the above-described polyacrylic acid resin. If abranched-chain alkanol, instead of a straight-chain alkanol, is used asthe dispersion medium, the solubility and stability of the polyacrylicacid resin in the dispersion medium will be significantly lowered,making it difficult to keep dispersion stability at an appropriatelevel. However, the present invention should not be construed as beinglimited to this.

Concrete examples of the straight-chain alkanol with 2 to 5 carbon atomsaccording to the present invention may include ethanol, n-propanol,n-butanol, and n-pentanol; preferably, at least one among ethanol,n-protanol, n-butanol, and n-pentanol; more preferably, n-propanol.

The content of the alkanol according to the present invention is notspecifically limited, but may be, for example, 50 to 99.93 wt % of thetotal weight of the composition; preferably, 80 to 99 wt %. Within thisrange, the viscosity of the dispersion liquid may be kept low, therebyfurther improving the dispersion stability of the carbon nanotubes, andthe alkanol may be mixed effectively with a binder component when usedin a coating film.

Additional Dispersant

A carbon nanotube dispersion liquid composition according to the presentinvention may further comprise an additional dispersant, and theadditional dispersant is not limited to a specific type, but may be, forexample, an acrylic block copolymer dispersant.

In the present invention, the term “acrylic block copolymer” refers to acopolymer made up of blocks of different polymerized acrylicmonomers—for example, a copolymer with A and B monomer units arranged inthe pattern of AAAAAABBBBBB. The acrylic block copolymer may furtherimprove dispersion stability by separating the polarity of a carbonylgroup in the copolymer. Preferably, each monomer unit in the acrylicblock copolymer may comprise at least one functional group such as anamine group, carboxyl group, etc., and the ratio between hydrophilic andhydrophobic components may be adjusted by adjusting the content ofmonomer units comprising the substituent, thereby further improving thedispersibility of carbon nanotubes. Concrete examples of the acryliccopolymer dispersant available on the market may include polymerdispersants DISPERBYK 2001 and DISPERBYK 2155 from BYK company.

The content of the additional dispersant is not specifically limited,but may be, for example, 0.1 to 2 wt % of the total weight of thecomposition; preferably, 0.5 to 1 wt %. Within this range, it ispossible to prevent degradation in scratch resistance and increase inviscosity due to the use of the additional dispersant, and thedispersion stability may be effectively maintained.

The carbon nanotube dispersion liquid composition of this invention maycontain a very small amount of water as required. Water may be used toimprove the solubility and dispersibility of the above-describedcomponents. For example, water may be used as a solvent for improvingthe dispersion activity of the polyacrylic acid resin, but the presentinvention is not limited to this.

Method of Preparing Carbon Nanotube Dispersion Liquid Composition

A method of preparing a carbon nanotube dispersion liquid comprising theabove-described components will be described below.

First, carbon nanotubes, polyacrylic acid resin, and a straight-chainalkanol with 2 to 5 carbon atoms are mixed together. The polyacrylicacid resin may be prepared in aqueous solution in advance before themixing. The concentration of the aqueous solution is not specificallylimited, but the solid content of the polyacrylic acid resin may bepreferably 0.02 to 40 wt % of the total content of the carbon nanotubedispersion liquid composition, more preferably, 20 to 30 wt %. Thespecific type and content of each component of the carbon nanotubedispersion liquid composition are as described above.

Next, the respective components of the carbon nanotube dispersion liquidare mixed together, and then dispersed at a high pressure of 1,000 to1,800 bar. When dispersed under a high pressure of 1,000 to 1,800 bar,the carbon nanotubes may collide with each other with an appropriateshear stress, and therefore carbon nanotube strands may be effectivelydispersed. As a result, the carbon nanotubes are homogeneously dispersedin the composition without aggregation, thereby effectively promotinginteractions between the polyacrylic acid resin and the alkanol.

When dispersed at a pressure below 1,000 bar, the energy delivered tothe carbon nanotubes is low, thus significantly reducing the dispersioneffect. At a pressure above 1,800 bar, the polymer chains of thepolyacrylic acid resin may break apart due to excessively high energy,and this may reduce the steric hindrance effect, thereby loweringdispersion stability. More preferably, the dispersion pressure may be1,200 to 1,600 bar, in which case, the above-described effects may befurther improved.

The dispersion may be performed by jetting the composition through anozzle with a predetermined diameter in the above-mentioned pressurerange. The diameter of the nozzle through which the composition isjetted may be 50 to 400 preferably, 80 to 200 Moreover, the dispersionmay be performed simultaneously by using nozzles of different sizesconnected in series, or twice separately by using the respectivenozzles.

By using nozzles within the above diameter range, the process may beperformed easily at a high temperature of 1,000 to 1,800 bar, asdescribed above, thereby achieving effective dispersion.

The diameter and flow rate of nozzles may be chosen within anappropriate range to match the pressure range.

Moreover, a stirring process may be performed prior to the high-pressuredispersion process. This may optimize the mixing of the composition,thereby further improving the efficiency of the high-pressure dispersionprocess.

[Conductive Coating Liquid Composition]

Hereinafter, a conductive coating liquid composition comprising 10 to100 parts by weight of a silane sol based on 100 parts by weight of theabove-described carbon nanotube dispersion liquid composition will bedescribed.

<Carbon Nanotube Dispersion Liquid Composition>

The carbon nanotube dispersion liquid composition may contain the samecomponents in the same proportions, and may be prepared by high-pressuredispersion.

<Silane Sol>

A silane sol according to the present invention acts as a binder in thecoating liquid composition, and may contain an alkoxysilane compound, anacid catalyst, an alcohol-based solvent, and water.

Alkoxysilane Compound

An alkoxysilane compound according to the present invention is a binderresin, and is not limited to a specific type. Examples of thealkoxysilane compound may include: tetraalkoxysilane compounds, such astetraethoxysilane, tetramethoxysilane, and tetra-n-propoxysilane;alkylalkoxysilanes of substituted or unsubstituted, straight- orbranched-chain alkyl groups, such as methyltrimethoxysilane,methyltriethoxysilane, ethyltriethoxysilane, ethyltrimethoxysilane,methyltripropoxysilane, methyltributoxysilane, propyltrimethoxysilane,propyltriethoxysilane, isobutyltriethoxysilane,isobutyltrimethoxysilane, octyltriethoxysilane, octyltrimethoxysilane,and methacryloxydecyltrimethoxysilane; phenyltrimethoxysilane,phenyltriethoxysilane, phenyltripropoxysilane, andphenyltributoxysilane; 3-aminopropyltrimethoxysilane,3-aminopropyl-triethoxysilane,2-aminoethyl-3-aminopropyltrimethoxysilane,N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane,N-(n-butyl)-3-aminopropyltrimethoxysilane,3-aminopropylmethyldiethoxysilane; dimethyldimethoxysilane,diethyldiethoxysilane, γ-glycidyloxypropyltrimethoxysilane,γ-glycidyloxypropyltrimethoxysilane, vinyltrimethoxysilane,vinyltriethoxysilane, 3-mercaptopropyltrimethoxysilane; andfluoroalkylsilanes, such astridecafluoro-1,1,2,2-tetrahydrooctyltriethoxysilane,trifluoropropyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane,and heptadecafluorodecyltriisopropoxysilane. These may be used alone, ortwo or more of these alkoxysilane compounds may be used in combination.

Of these, an alkylalkoxysilane compound with an alkyl group of 1 to 20carbon atoms is most preferable, and more preferably, atetraethoxysilane compound may be used.

The content of the alkoxysilane compound according to the presentinvention is not specifically limited, but may be, for example, 20 to 60wt % of the total weight of the silane sol; preferably, 30 to 50 wt %.Within this range, a sol-gel reaction occurs readily, and therefore theobtained silane sol has good physical properties and high adhesion,thereby facilitating the formation of a coating film and making it moresuitable, especially for coating a glass substrate.

Acid Catalyst

An acid catalyst according to the present invention is used to promotethe hydrolysis of water and alkoxysilane and provide an appropriatedegree of crosslinking. A weak acid aqueous solution with a pH of 3.0 to6.0 may be used as the acid catalyst.

In the present invention, the acid catalyst performs two importantactions. First, the acid catalyst delays the reduction process of curingdefects in carbon nanotubes. As shown in FIG. 9, defects such as OH—,O₂, etc. exist in the carbon nanotubes, and the lower the pH of thecomposition, the more quickly these defects in the carbon nanotubes arecured and the higher the electrical conductivity. By using a weak acidwith a pH of 3.0 to 6.0 as the acid catalyst of this invention, thereduction process of curing defects in the carbon nanotubes worksslowly. With this slow reduction process of curing defects in the carbonnanotubes, the composition undergoes little change in sheet resistance,thereby improving the storage stability of the composition when left atroom temperature.

Second, the acid catalyst controls the gel reaction speed of the silanesol. As shown in FIG. 10, the gel reaction time gets slower as the pHgoes from 2 to 8. In the present invention, an acid catalyst with a pHof 3.0 to 6.0 is used to slow down the gel reaction speed of the silanesol. By slowing down the gel reaction speed of the silane sol, the finalcomposition undergoes less change in viscosity, thereby improving thestorage stability of the composition when left at room temperature.

Accordingly, the present invention may use an acid catalyst with a pH of3.0 to 6.0, and examples of the acid catalyst may include phosphoricacid, hydrogen fluoride, benzoic acid, carbonic acid, and hydrogensulfide. These acid catalysts may be used alone, or two or more kinds ofthem may be used in combination. The acid catalyst used may exist inaqueous solution when mixed. Here, if the pH of the acid catalyst is 3.0or higher, this slows down the reduction process of the carbon nanotubesand the gel reaction of the silane sol, thereby improving the storagestability of the composition. If the pH of the acid catalyst is 6.0 orlower, the hydrolysis and condensation reactions of the silane sol donot occur properly, thereby preventing the formation of a thin film.

The content of the acid catalyst according to the present invention isnot specifically limited, but may be, for example, 0.01 to 10 wt % ofthe total weight of the silane sol; preferably, 0.05 to 5 wt %. Withinthis range, it is possible to form a coating film with an appropriatedegree of crosslinking.

Alcohol-Based Solvent

The type of an alcohol-based solvent according to the present inventionis not specifically limited, but a hydrophilic alcohol-based solvent maybe preferably used in terms of compatibility with a carbon nanotubedispersion liquid, and examples of the alcohol-based solvent may includemethanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol,sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amylalcohol, tert-amyl alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol,n-hexanol, and cyclohexanol. These alcohol-based solvents may be usedalone, or two or more kinds of them may be used in combination. Ofthese, in terms of improvement in stability with the carbon nanotubedispersion liquid, ethanol, n-butanol, n-propanol, and n-pentanol arepreferably used; more preferably, n-propanol may be used.

The content of the alcohol-based solvent according to the presentinvention is not specifically limited, but may be, for example, 10 to 70wt % of the total weight of the silane sol; preferably, 20 to 50 wt %.Within this range, the reactivity of the sol-gel reaction may be furtherimproved.

Water

Water according to the present invention is a component that undergoes ahydrolysis reaction with alkoxysilanes, and the water content is notspecifically limited, but may be, for example, 5 to 60 wt % of the totalweight of the silane sol, preferably 8 to 35 wt %. Within this range,alkoxysilanes are hydrolyzed well enough to provide high adhesion to asubstrate.

Polar Solvent

A polar solvent according to the present invention is used to improvethe dispersibility of carbon nanotubes in the conductive coating liquidcomposition and improve electrical conductivity. The polar solvent has apolarity of 10 or higher.

The polar solvent according to the present invention maximizesdispersibility by increasing the force of repulsion of a carboxyl groupof polyacrylic acid resin surrounding the carbon nanotubes in thedispersion liquid. This enhances the distribution of the carbonnanotubes acting as conductive fillers in the form of a coating film,thereby improving electrical conductivity. For instance, referring toFIG. 9, if a solvent with a low polarity is comprised in the conductivecoating liquid composition, the force of repulsion of the carboxyl groupof the polyacrylic acid resin surrounding the carbon nanotubes is low,thereby leading to low dispersibility. On the other hand, referring toFIG. 10, if a solvent with a high polarity is comprised in theconductive coating liquid composition, the force of repulsion of thecarboxyl group of the polyacrylic acid resin surrounding the carbonnanotubes is high, thereby leading to high dispersibility.

In addition, the polar solvent according to the present invention helpsensure a proper viscosity at the time of coating, and regulates thedrying rate to an appropriate range at the time of coating, therebyobtaining a uniform coating film.

The polar solvent according to the present invention has a polarity of10 or higher, and examples thereof may include n-methyl pyrolidone(NMP), dimethyl sulphoxide (DMSO), and dimethyl formamide (DMF).N-methyl pyrolidone (NMP), dimethyl sulphoxide (DMSO), and dimethylformamide (DMF) may contribute to further improvement of electricalconductivity, especially because of their inherent dielectric constants,thus making them more suitable for forming a low-resistance coatingfilm.

The content of the polar solvent according to the present invention maybe 0.1 to 5 wt % based on 100 wt % of the conductive coating liquidcomposition. If the polar solvent content is 0.1 wt % or higher based on100 wt % of the conductive coating liquid composition, this may improvethe dispersibility of the carbon nanotubes and thus improve surfaceresistance uniformity, making it easy to adjust surface resistance. Ifthe polar solvent content is 5 wt % or lower based on 100 wt % of theconductive coating liquid composition, this may prevent the surfaceresistance of an antistatic film made of the conductive coating liquidcomposition from getting too low.

Additives

A conductive coating liquid composition according to the presentinvention may further contain additives as required, in addition to theabove-described carbon nanotube dispersion liquid and silane sol.

Usable additives may include a dispersant, a silane coupling agent, aleveling agent, a slip agent, a surfactant, a pH adjuster, a retardersolvent, a viscosity regulator, etc., but are not limited to them. Theseadditives may be used alone, or two or more kinds of them may be used incombination.

In a more concrete example, the conductive coating liquid compositionmay further contain a slip agent for improving the slip properties of acoating film. The slip agent is not limited to a specific type, andcommercially available examples of the slip agent may include, but arenot limited to, BKY 333 of BYK company. Also, the aforementioneddispersant, BKY 2001, may be further used.

Moreover, polar solvents such as ethylenglycol, dimethylformamide, and1-methyl-2pyrrolydone maximize dispersibility by increasing the force ofrepulsion of a carboxyl group of polyacrylic acid resin surrounding thecarbon nanotubes in the dispersion liquid. This enhances thedistribution of the carbon nanotubes acting as conductive fillers in theform of a coating film, thereby improving electrical conductivity. Inaddition, they help ensure a proper viscosity at the time of coating,and regulate the drying rate to an appropriate range at the time ofcoating, thereby obtaining a uniform coating film. Further,ethyleneglycol, dimethylformamide, and 1-methyl-2pyrrolydone maycontribute to further improvement of electrical conductivity because oftheir intrinsic dielectric constants, thus making them more suitable forforming a low-resistance coating film.

The additional additives may be used alone, or two or more kinds of themmay be used in combination. Their content is not specifically limited,but may be, for example, 0.01 to 10 wt % of the total weight of theconductive coating liquid composition; preferably, 0.1 to 5 wt %. Withinthis range, the above-mentioned additives may achieve their uniqueeffects without hindering the effects of this invention.

The silane sol according to the present invention may be prepared bygetting the above-described components to react to a predeterminedcondition. The reaction condition is not specifically limited, but maycomprise, for example, a process of heating and stirring them at 30 to90° C., and the reaction time is not specifically limited, but may be,for example, 4 to 30 hours. The reactor where reaction takes place maycomprise a reflux condenser tube. After the reaction, the product may berotavated, concentrated, and then diluted in a particular solvent. Thus,the prepared silane sol may provide strong adhesion, especially when thecoating liquid is applied to a glass substrate, and therefore achievesuperior strength characteristics.

<Preparation of Conductive Coating Liquid Composition>

A conductive coating liquid composition according to the presentinvention may be prepared by making a carbon nanotube dispersion liquidand a silane sol, separately, and then mixing the carbon nanotubedispersion liquid and the silane sol together.

The conductive coating liquid composition according to the presentinvention may be prepared by mixing 10 to 100 parts by weight of thesilane sol based on 100 parts by weight of the carbon nanotubedispersion liquid composition.

If the silane sol content in the mixture is less than 10 parts byweight, it is difficult to give the coating layer adhesive force. If thesilane sol content in the mixture is more than 100 parts by weight, thecoatability of the coating layer may be degraded. Moreover, the silanesol may be mixed in 25 to 60 parts by weight or 10 to 20 parts byweight, based on 100 parts by weight of the carbon nanotube dispersionliquid composition. If the silane sol content in the mixture is 25 to 60parts by weight, the silane sol is suitable for forming ahigh-resistance coating film. If the silane sol content in the mixtureis 10 to 20 parts by weight, the silane sol is suitable for forming alow-resistance coating film.

The mixing method is not specifically limited, but may be performed byusing an ultrasonic disperser, a high-pressure disperser, a homogenizer,a mill, etc. Preferably, the dispersion and stability of the finalcoating liquid may be achieved by using the same high-pressuredispersion process as in the preparation of the carbon nanotubedispersion liquid.

A coating film made of the conductive coating liquid compositioncomprising the above-described components may provide uniform andexcellent electrical conductivity and excellent mechanical strength,thereby making it suitable for use in image displays.

<Display Device>

A display device having an antistatic film made of the above conductivecoating liquid composition will be described. An in-cell touch displayaccording to an exemplary embodiment of the present invention will bedescribed below in detail.

FIGS. 11 and 12 are views schematically showing a display deviceaccording to the present invention. FIG. 13 is a waveform diagramshowing a common voltage Vcom and touch driving signal Tdriv applied tothe touch sensors Cs of FIG. 11.

Referring to FIGS. 11 to 13, a display device comprises a touch sensingdevice. The touch sensing device detects touch input by using touchsensors Cs embedded in a display panel 300. The touch sensing device isable to detect touch input based on a change in the capacitance of thetouch sensors Cs because the capacitance increases when a finger makescontact with a self-capacitive touch sensor Cs.

A liquid crystal layer is formed between two substrates on the displaypanel 300. Liquid crystal molecules are driven by an electric fieldgenerated by the potential difference between a data voltage applied toa pixel electrode 12 and a common voltage Vcom applied to a sensorelectrode 13. A pixel array on the display panel 300 comprises pixelsdefined by data lines S (S1 to Sm; m is a positive integer) and gatelines G (G1 to Gn; n is a positive integer) and touch sensors connectedto the pixels.

A touch sensor Cs comprises a sensor electrode and a sensor line M3connected to the sensor electrode. Sensor electrodes COM (C1 to C4) maybe patterned by splitting the existing common electrode. Each of thesensor electrodes COM (C1 to C4) overlaps a plurality of pixels. Thesensor electrodes COM (C1 to C4) receive, through the sensor lines M3, acommon voltage Vcom during a display driving period Td and a touchdriving signal Tdry during a touch sensor driving period Tt. The commonvoltage Vcom is applied commonly to the pixels through the sensorelectrodes.

The sensor lines M3 are arranged at boundaries between subpixels,bypassing the area where a spacer will be. The sensor lines M3 mayoverlap the data lines S1 to Sm, with an insulating layer (not shown)between them, in order to avoid any reduction in the apertures of thepixels.

Since the touch sensors are embedded in the pixel array on the displaypanel 300, the touch sensors Cs are connected to the pixels throughparasitic capacitance. In the present invention, in order to reduce theeffects of mutual coupling between the pixels and the touch sensors Cs,as shown in FIG. 13, 1 frame period is time-split into a period fordriving the pixels (hereinafter, “display driving period”) and a periodfor driving the touch sensors (hereinafter, “touch sensor drivingperiod”) to drive the touch sensors. 1 frame period may be split into atleast one display driving period Td and at least one touch sensordriving period Tt. During the display driving period Td, data of aninput image is written to the pixels. During the touch sensor drivingperiod TT, the touch sensors are driven to detect touch input.

The pixels comprise thin film transistors TFT formed at theintersections of the data lines S1 to Sm and the gate lines G1 to Gn,pixel electrodes that receive a data voltage through the TFTs of thepixels, a common electrode to which a common voltage Vcom is applied,and storage capacitors Cst connected to the pixel electrodes to maintainthe voltage of the liquid crystal cell.

A black matrix, color filters, etc. may be formed on the upper substrateof the display panel 300. The lower substrate of the display panel 300may be implemented in a COT (color filter on TFT) structure. In thiscase, the color filters may be formed on the lower substrate of thedisplay panel 100. Polarizers are respectively attached to the upper andlower substrates of the display panel 300, and an alignment film forsetting a pre-tilt angle of liquid crystals is formed on an innersurface contacting the liquid crystals. A spacer is formed between theupper and lower substrates of the display panel 300 to maintain a cellgap for the liquid crystal layer.

A backlight unit may be disposed under the back of the display panel300. The backlight unit is an edge-type or direct-type backlight unitwhich illuminates the display panel 300. The display panel 300 may beimplemented in any well-known liquid crystal mode, such as a TN (TwistedNematic) mode, a VA (Vertical Alignment) mode, an IPS (In-PlaneSwitching) mode, and an FFS (Fringe Field Switching) mode. Aself-emitting display device such as an organic light-emitting diodedisplay requires no backlight unit.

The display device according to the present invention further comprisesa display drive part 302, 304, and 306 that writes data of an inputimage to the pixels and a touch sensor driver 310 that drives the touchsensors Cs. The display drive part 302, 304, and 306 and the touchsensor driver 310 are synchronized with each other in response to asynchronization signal Tsync.

The display drive part 302, 304, and 306 writes data to the pixelsduring the display driving period Td. The pixels hold the data voltagestored during the preceding display driving period Td because the TFTsare in the off state during the touch sensor driving period Tt. Thedisplay drive part 302, 304, and 306 may feed an alternating currentsignal having the same phase as the touch driving signal Tdry applied tothe touch sensors Cs to the signal lines S1 to Sm and G1 to Gn, in orderto minimize the parasitic capacitance between the touch sensors Cs andthe signal lines connected to the pixels during the touch sensor drivingperiod Tt. Here, the signal lines connected to the pixels are the datalines S1 to Sm and the gate lines G1 to Gn.

The display drive part 302, 304, and 306 comprises a data driver 302, agate driver 304, and a timing controller 306.

During the display driving period Td, the data driver 302 convertsdigital video data RGB or RGBW of an input image received from thetiming controller 306 to an analog positive/negative gamma compensationvoltage to generate a data voltage, and outputs the data voltage outputfrom the data driver 302 to the data lines S1 to Sm. During the touchsensor driving period Tt, the data driver 302 may apply an alternatingcurrent signal having the same phase as the touch driving signal Tdryapplied to the touch sensors to the data lines S1 to Sm. This is becausethe voltages at both ends of the parasitic capacitance changesimultaneously and the smaller the voltage difference, the less theamount of electric charge stored in the parasitic capacitance.

During the display driving period Td, the gate driver 304 sequentiallysupplies a gate pulse (or scan pulse) synchronized with the data voltageto the gate lines G1 to Gn and selects lines of the display panel 100 towhich the data voltage is written. The gate pulse swings between a gatehigh voltage VGH and a gate low voltage VGL. The gate pulse is appliedto the gates of the pixel TFTs through the gate lines G1 to Gn. The gatehigh voltage VGH is set to a voltage higher than a threshold voltage ofthe pixel TFTs and turns on the pixel TFTs. The gate low voltage VGL isa voltage lower than the threshold voltage of the pixel TFTs. The gatedriver 304 applies an alternating current signal having the same phaseas the touch driving signal Tdry applied to the touch sensors during thetouch sensor driving period Tt to the gate lines G1 to Gn.

The timing controller 306 receives timing signals, such as a verticalsynchronization signal Vsync, a horizontal synchronization signal Hsync,a data enable signal DE, and a main clock MCLK from a host system 308,and synchronizes the operation timings of the data driver 302, gatedriver 304, and touch sensor driver 310. A scan timing control signalcomprises a gate start pulse GSP, a gate shift clock, a gate outputenable signal GOE, etc. A data timing control signal comprises a sourcesampling clock SSC, a polarity control signal POL, a source outputenable signal SOE, etc.

The timing controller 306 transmits input image data RGB form the hostsystem 308 to the data driver 302. The timing controller 306 may convertRGB data to RGBW data by a well-known white gain calculation algorithmand transmit it to the data driver 302.

The host system 308 may be implemented as any one of the following: atelevision system, a set-top box, a navigation system, a DVD player, aBlue-ray player, a personal computer PC, a home theater system, and aphone system. The host system 308 comprises a system-on-chip (SoC)having a scaler incorporated therein, and converts digital video data ofan input image into a format suitable for the resolution of the displaypanel 300. The host system 308 transmits the digital video data RGB orRGBW of the input image and the timing signals to the timing controller306. Further, the host system 308 executes an application associatedwith coordinate information XY of touch input from the touch sensordriver 310.

The timing controller 306 or the host system 308 may generate asynchronization signal Tsync for synchronizing the display driving part302, 304, and 306 and the touch sensor driver 310.

The touch sensor driver 310 generates a touch driving signal Tdry duringthe touch sensor driving period Tt. The touch driving signal Tdry issupplied to the sensor electrodes 13 or C1 to C4 through the sensorlines M3. The touch sensor driver 310 may detect the location and areaof a touch by measuring a change in the capacitance of the touch sensorsCs. The touch sensor driver 310 calculates coordinate information XY ofthe touch input and transmits it to the host system 308.

The data driver 302 and the touch sensor driver 310 may be integratedwithin a single IC (Integrated Circuit).

FIG. 14 is a cross-sectional view showing a cross-sectional structure ofthe display panel 300.

Referring to FIG. 14, a bottom plate of the display panel 300 comprisesa TFT array on a lower substrate SUBS1. A top plate of the display panel300 comprises a color filter array on an upper substrate SUBS2. A liquidcrystal layer LC is formed between the top and bottom plates of thedisplay panel 300.

A buffer insulating film BUF, a semiconductor pattern ACT, and a gateinsulating film GI are formed on the lower substrate SUBS1. A firstmetal pattern is formed on the gate insulating film GI. The gate metalpattern comprises gates GE of TFTs and gate lines G1 to Gn connected tothe gates GE. An interlayer insulating film INT covers a second metalpattern. A source-drain metal pattern is formed on the interlayerinsulating film INT. The second metal pattern comprises data lines S1 toSm and sources SE and drains DE of the TFTs. The drains DE areaconnected to the data lines S1 to Sm, and the sources SE and drains DEof the TFTs. The drains DE are connected to the data lines S1 to Sm. Thesources SE and drains DE of the TFTs come into contact with thesemiconductor pattern ACT of the TFTs via contact holes through theinterlayer insulating film INT.

A first passivation film PAS1 covers the second metal pattern. A secondpassivation film PAS2 is formed on the first passivation film PAS1.Contact holes exposing the sources SE of the TFTs are formed in thesecond passivation film PAS. A third passivation film PAS3 is formedover the second passivation film PAS2, and a third metal pattern isformed on the third passivation film PAS3. The third metal patterncomprises sensor lines M3. A fourth passivation film PAS4 is formed overthe third passivation film PAS3 to cover the third metal pattern. Afourth metal pattern is formed on the fourth passivation film PAS4. Thefourth metal pattern comprises sensor electrodes 13 or COM made of atransparent electrode material such as ITO (indium tin oxide). A fifthpassivation film PAS5 is formed over the fourth passivation film PAS4 tocover the fourth metal pattern. The first, third, fourth, and fifthpassivation films PAS1, PAS3, PAS4, and PAS5 may be made of an inorganicinsulating material such as SiOx or SiNx. The second passivation filmPAS2 may be made of an organic insulating material such as photo-acryl.

The third, fourth, and fifth passivation films PAS1, PAS3, PAS4, andPAS5 comprise contact holes patterned to expose the sources SE of theTFTs. A fifth metal pattern is formed on the fifth passivation filmPAS5. The fifth metal pattern comprises pixel electrodes 12 or PXL madeof a transparent electrode such as ITO. An alignment film ALM is formedon the fifth passivation film PAS5 to cover the fifth metal patternPAS5.

A black matrix BM and color filters CF are formed on the upper substrateSUBS2, and a planarization film OC is formed on them. The planarizationfilm OC may be made of an organic insulating material. Although notshown, a spacer is formed between the upper substrate and the lowersubstrate, thereby maintaining a cell gap for the liquid crystal layer.

An antistatic film 250 according to the present invention is formed onthe upper substrate SUBS2. The antistatic film 250 according to thepresent invention exhibits excellent electrical conductivity andexcellent mechanical strength and transmittance, so it may be used as anantistatic coating film for touchscreen panels and display devices. Themethod of forming the antistatic film 250 is not specifically limited,but may be formed by applying and curing a conductive coating liquidcomposition according to the present invention. The method ofapplication is not specifically limited, but may include well-knownmethods such as slit coating, knife coating, spin coating, casting,micro gravure coating, gravure coating, bar coating, roll coating, wirebar coating, dip coating, spray coating, screen printing, gravureprinting, flexo printing, offset printing, inkjet printing, dispenserprinting, nozzle coating, capillary coating, etc. After the application,the coating film is cured by drying at a given temperature, therebyforming the antistatic film 250.

FIGS. 15 to 17 are views schematically showing various display devicesto which an antistatic film of this invention applies.

Referring to FIG. 15, a display device according to an exemplaryembodiment of the present invention comprises a display panel 300 whichis formed by joining a lower substrate SUBS1 with a thin-film transistorarray and an upper substrate SUBS2 with a color filter array together,and a cover window COV on the display panel 300. An antistatic film 250according to the present invention may be attached to both surfaces ofthe display panel 300. That is, the antistatic film 250 may be disposedbetween the lower substrate SUBS1 and a lower polarizer LPOL, and theantistatic film 250 also may be disposed between the upper substrateSUBS2 and an upper polarizer HPOL. In this case, the antistatic film 250is used for the purpose of reducing touch noise, and the lower the sheetresistance, the higher the noise-reducing effect. As for in-cell typetouch devices, a sheet resistance of 10⁶ to 10⁹ Ω/sq is required, and asfor add-on type touch devices, the lower the sheet resistance, thebetter.

Referring to FIGS. 16 and 17, a display device according to an exemplaryembodiment of the present invention comprises a display panel 300 havinga lower substrate SUBS3 with a color filter array and an upper substrateSUBS4 with a thin-film transistor array, and a cover window COV on thedisplay panel 300. The display device shown in FIGS. 16 and 17 emitlight upward, like the above-described display device of FIG. 15, butits color filer array and thin-film transistor are inverted unlike inFIG. 15. In this case, as shown in FIG. 16, the antistatic film 250 maybe disposed between the upper substrate SUBS4 where the thin-filmtransistor is formed and the upper polarizer HPOL. On the other hand, asshown in FIG. 17, the antistatic film 250 may be disposed between theupper substrate SUBS4 where the thin-film transistor is formed and theupper polarizer HPOL and also between the lower substrate SUBS3 wherethe color filter array is formed and the lower polarizer LPOL. However,the present invention is not limited to this, and the antistatic filmmay be attached to any surface of various types of display devices.

Hereinafter, experimental examples will be provided to helpunderstanding of the present invention. These examples are onlyexemplary and do not limit the attached claims. It will be apparent tothose of ordinary skill in the art that various changes andmodifications can be made thereto within the scope and technical spiritof the present disclosure and that such changes and modifications belongto the attached claims.

Second Experimental Example

Hereinafter, disclosed is an experimental example in which an antistaticfilm is formed using the above-described carbon nanotube dispersionliquid composition and a conductive coating liquid compositioncomprising the same.

Experiment 1: Measurement of Characteristics of Conductive CoatingLiquid Composition and Coating Film (Antistatic Film) ManufacturedTherefrom

Example 1

<Preparation of Carbon Nanotube Dispersion Liquid>

Carbon nanotubes (SA100, Nano Solution Inc.) synthesized by an arcdischarge method were thermally treated for 100 minutes under a rotationspeed of 5-20 rpm, a temperature of 420° C., and an oxidative gas supplyrate of 250 cc/min, using a rotary kiln reactor with an inclinationangle of 3°, to obtain carbon nanotubes A having an impurity content of15%, which were then used.

After that, a carbon nanotube dispersion liquid was prepared by mixing0.15 parts by weight of carbon nanotubes A, 0.24 parts by weight of anaqueous solution of a polyacrylic acid resin (solid 25%/polyacrylic acidresin Mw=(250,000)), 0.23 parts by weight of an acrylic block copolymer(product name: DISPERBYK2001, acid value: 19 mgKOH/g, amine value: 29mgKOH/g), and 99.61 parts by weight of n-propanol, and dispersing themixture using a disperser with a nozzle diameter of 100 μm at a pressureof 1,500 bar.

<Preparation of Silane Sol>

21.7 parts by weight of normal propanol and 62.6 parts by weight of TEOSwere fed into a reactor with a flux tube, and stirred at 300 rpm underroom temperature (25° C.) using a stirrer for 30 minutes. Then, 15.2parts by weight of water was added thereto, followed by stirring at 500rpm, and then 0.5 parts by weight of a 3.5% aqueous solution ofhydrochloric acid was slowly dropped.

<Conductive Coating Liquid Composition>

A coating liquid was prepared by conducting a procedure, five times, inwhich 33 parts by weight of a binder, 0.95 parts by weight of BYK2001,and 0.05 parts by weight of BYK333 as a surface slip agent were added to66 parts by weight of the prepared carbon nanotube dispersion liquid andthen the mixture was allowed to pass through a 100 μm nozzle under apressure of 1,500 bar using a high-pressure disperser. Here, a coolingapparatus was used to reduce or prevent the rise of the liquidtemperature.

Example 2 (when the Type of Dispersion Medium is Different)

A conductive coating liquid composition was produced by the same methodas in Example 1 except that ethanol was used as a dispersion medium atthe time of preparing a carbon nanotube dispersion liquid.

Example 3 (when the Type of Dispersion Medium is Different)

A conductive coating liquid composition was produced by the same methodas in Example 1 except that butanol was used as a dispersion medium atthe time of preparing a carbon nanotube dispersion liquid.

Example 4 (when the Type of Dispersion Medium is Different)

A conductive coating liquid composition was produced by the same methodas in Example 1 except that pentanol was used as a dispersion medium atthe time of preparing a carbon nanotube dispersion liquid.

Example 5 (when the Weight Average Molecular Weight of PAA is Different

A conductive coating liquid composition was produced by the same methodas in Example 1 except that a polyacrylic acid resin having a weightaverage molecular weight of 1,250,000 was used at the time of preparinga carbon nanotube dispersion liquid.

Example 6 (when BYK 2155 is Used)

A conductive coating liquid composition was produced by the same methodas in Example 1 except that DISPERBYK 2155 was used instead of DISPERBYK2001 at the time of preparing a carbon nanotube dispersion liquid.

Example 7 (when the Jetting Pressure is Different)

A conductive coating liquid composition was produced by the same methodas in Example 1 except that jetting was conducted at a pressure of 1,000bar at the time of preparing a carbon nanotube dispersion liquid.

Example 8 (when the Jetting Pressure is Different)

A conductive coating liquid composition was produced by the same methodas in Example 1 except that jetting was conducted at a pressure of 1,800bar at the time of preparing a carbon nanotube dispersion liquid.

Example 9 (when the Diameter of the Jet Nozzle is Different)

A conductive coating liquid composition was produced by the same methodas in Example 1 except that jetting was conducted using a nozzle with adiameter of 500 μm at the time of preparing a carbon nanotube dispersionliquid.

Example 10 (when the Diameter of the Jet Nozzle is Different)

A conductive coating liquid composition was produced by the same methodas in Example 1 except that jetting was conducted using a nozzle with adiameter of 300 μm at the time of preparing a carbon nanotube dispersionliquid.

Example 11

A coating liquid was prepared by conducting a procedure, five times, inwhich 14 parts by weight of a binder, 0.95 parts by weight of BYK2001, 5parts by weight of ethylene glycol, and 0.05 parts by weight of BYK333as a surface slip agent were added to 80 parts by weight of the preparedcarbon nanotube dispersion liquid and then the mixture was allowed topass through a 100 μm nozzle under a pressure of 1,500 bar using ahigh-pressure disperser. Here, a cooling apparatus was used to reduce orprevent the rise of the liquid temperature.

Comparative Example 1 (when the Type of Dispersion Medium Departs fromthe Scope of the Present Invention)

A conductive coating liquid composition was produced by the same methodas in Example 1 except that isopropanol was used as a dispersion mediumat the time of preparing a carbon nanotube dispersion liquid.

Comparative Example 2 (when Sodium Dodecyl Sulfonate was Used asDispersion Medium, Instead of PAA)

A conductive coating liquid composition was produced by the same methodas in Example 1 except that an aqueous solution of sodium dodecylsulfonate was used instead of the aqueous solution of polyacrylic acidat the time of preparing a carbon nanotube dispersion liquid.

Comparative Example 3 (when Isopropanol is Used and the Jet PressureDeparts from the Scope of the Present Invention)

A conductive coating liquid composition was produced by the same methodas in Example 1 except that jetting was conducted at a pressure of 900bar at the time of preparing a carbon nanotube dispersion liquid.

Comparative Example 4 (when Isopropanol is Used and the Jet PressureDeparts from the Scope of the Present Invention)

A conductive coating liquid composition was produced by the same methodas in Example 1 except that jetting was conducted at a pressure of 2,000bar at the time of preparing a carbon nanotube dispersion liquid.

Test Method

(1) Evaluation of Dispersibility

In order to evaluate the carbon nanotube dispersion liquid compositionsproduced according to the examples and comparative examples, the Zetapotential was measured, and evaluation was conducted on the basis of thefollowing evaluation standard.

<Evaluation Standard>

◯: Absolute value of more than 25 mV

Δ: Absolute value in the range of 10 to 25 mV

x: Absolute value of less than 10 mV

(2) Evaluation on Dispersion Stability

It was evaluated whether or not the carbon nanotube dispersion liquidcompositions produced according to the examples and comparative examplesaggregate in vials at room temperature for 30 days, on the basis of thefollowing evaluation standard.

<Evaluation Standard>

◯: Aggregated after 14 days

Δ: Aggregated after 7 days

x: Aggregated within 2 days

(3) Evaluation of Coatability

Conductive coating films were formed by coating the conductive coatingliquid compositions according to the examples and comparative exampleson glass substrates using a spin coater at 400 rpm for 15 seconds,conducting drying using a hot plate at 140° C. for 10 minutes, andconducting further drying using a hot-air dryer for 30 minutes. Theuniformity of the formed coating films was observed by naked eyes, andevaluation was conducted on the basis of the following evaluationstandard.

<Evaluation Standard>

◯: No pinholes

Δ: Less than 2 pinholes

x: 2 or more pinholes

(4) Evaluation on Surface Resistivity

Conductive coating films were formed by coating the conductive coatingliquid compositions according to the examples and comparative exampleson glass substrates using a spin coater at 400 rpm for 15 seconds,conducting drying using a hot plate at 140° C. for 10 minutes, andconducting further drying using a hot-air dryer for 30 minutes. Thesurface resistivity of the formed coating films was measured using asurface resistivity meter. Here, the measurement of the surfaceresistivity was conducted by a 4-point probe method. The coating filmwas divided into three equal parts lengthwise, and the measurement wasconducted at the middle portion thereof.

(5) Transmittance

Conductive coating films were formed by coating the conductive coatingliquid compositions according to the examples and comparative exampleson glass substrates using a spin coater at 400 rpm for 15 seconds,conducting drying using a hot plate at 140° C. for 10 minutes, andconducting further drying using a hot-air dryer for 30 minutes. Thetransmittance of the formed coating films was measured at 550 nm using aspectrophotometer, and evaluation was conducted compared with 90.5%,which is the transmittance of a glass substrate on which a coating filmwas not formed, on the basis of the following evaluation standard.

<Evaluation Standard>

◯: 89.5≤transmittance (%)

Δ: 87.5≤transmittance (%)<89.5

x: transmittance (%)<87.5

(6) Scratch Resistance

Conductive coating films were formed by coating the conductive coatingliquid compositions according to the examples and comparative exampleson glass substrates using a spin coater at 400 rpm for 15 seconds,conducting drying using a hot plate at 140° C. for 10 minutes, andconducting further drying using a hot-air dryer for 30 minutes. Thesurface hardness of the formed coating films was measured using a pencilhardness tester (221-D, Yoshimitsu).

<Evaluation Standard>

◯: 8˜9 H

Δ: 6˜7 H

x: ˜5 H

The dispersion characteristics, coatability, surface resistivity,transmittance, and scratch resistance of the coating films formedaccording to the examples and comparative examples were measured, andtabulated in Table 3 below. In Table 3 below, ◯ is excellent, Δ is good,and x is bad.

TABLE 3 Dispersion Characteristics Surface Disper- Resist- Trans-Scratch Dispers- sion Coat- ivity mittance Resist- ibility Stabilityability (Ω/sq) (%) ance Example 1 ◯ ◯ ◯ 10^(8.0) ◯ ◯ Example 2 ◯ ◯ ◯10^(8.0) ◯ ◯ Example 3 ◯ ◯ ◯ 10^(8.2) ◯ ◯ Example 4 ◯ Δ ◯ 10^(8.7) ◯ ◯Example 5 ◯ ◯ ◯ 10^(8.2) ◯ ◯ Example 6 ◯ ◯ ◯ 10^(8.1) ◯ ◯ Example 7 ◯ ◯◯ 10^(8.1) ◯ ◯ Example 8 ◯ ◯ ◯ 10^(8.3) ◯ ◯ Example 9 ◯ Δ ◯ 10^(8.1) ◯ ◯Example 10 ◯ Δ ◯ 10^(8.3) ◯ ◯ Example 11 ◯ ◯ ◯ 10^(5.0) ◯ ◯ ComparativeΔ X Δ 10^(8.2) ◯ ◯ Example 1 Comparative X X X 10^(9.4) X Δ Example 2Comparative Δ X Δ 10^(8.3) ◯ Δ Example 3 Comparative Δ X Δ 10^(8.5) ◯ ◯Example 4

Referring to Table 3 as for Examples 1 to 3 in which propanol, ethanol,and butanol were used as a solvent at the time of preparing the carbonnanotube dispersion liquid, the dispersibility, dispersion stability,coatability, transmittance, and scratch resistance were excellent, andthe surface resistivity values thereof were 10^(8.0), 10^(8.0), and10^(8.2) (Ω/sq), respectively. As for Example 4, the dispersibility,coatability, transmittance, and scratch resistance were excellent, thedispersion stability was good, and the surface resistivity value was10^(8.7) (Ω/sq).

As for Example 5 in which a polyacrylic acid resin having a weightaverage molecular weight of 1,250,000 was used and Example 6 in whichDISPERBYK 2155 was used, at the time of preparing the carbon nanotubedispersion liquid, the dispersibility, dispersion stability,coatability, transmittance, and scratch resistance were excellent, andthe surface resistivity values thereof were 10^(8.2) and 10^(8.1)(Ω/sq).

As for Example 7 in which jetting was conducted at a pressure of 1,000bar at the time of preparing the carbon nanotube dispersion liquid, thedispersibility, dispersion stability, coatability, transmittance, andscratch resistance were excellent, and the surface resistivity value was10^(8.1) (Ω/sq). In addition, as for Example 8 in which jetting wasconducted at a pressure of 1,800 bar, the dispersibility, coatability,transmittance, and scratch resistance were excellent while thedispersion stability was good, and the surface resistivity value was10^(8.3) (Ω/sq).

As for Examples 9 and 10 in which jetting was conducted using nozzleswith diameters of 500 μm and 300 μm at the time of preparing the carbonnanotube dispersion liquid, the surface resistivity values were 10^(8.1)and 10^(8.3) (Ω/sq), respectively, and the dispersibility, coatability,transmittance, and scratch resistance were excellent while thedispersion stability was good.

As for Example 11 in which 14 parts by weight of a binder, 0.95 parts byweight of BYK2001, and 5 parts by weight of ethylene glycol were addedto 80 parts by weight of the carbon nanotube dispersion liquid, thesurface resistivity value was 10^(5.0) (Ω/sq), and the dispersibility,dispersion stability, coatability, transmittance, and scratch resistancewere excellent.

On the other hand, as for Comparative Example 1 in which isopropanol wasused as a dispersion medium at the time of the carbon nanotubedispersion liquid, the surface resistivity value was 10^(8.2) (Ω/sq),and the transmittance and scratch resistance were excellent, but thedispersibility and coatability were good, and the dispersion stabilitywas bad.

As for Comparative Example 2 in which the aqueous solution of sodiumdodecyl sulfonate was used instead of the aqueous solution ofpolyacrylic acid at the time of preparing the carbon nanotube dispersionliquid, the surface resistivity value was 10^(9.4) (Ω/sq), and thescratch resistance was good, but the dispersibility, dispersionstability, coatability, and transmittance were bad.

As for Comparative Examples 3 and 4 in which isopropanol was used andjetting was conducted at 900 bar and 2,000 bar, respectively, at thetime of preparing the carbon nanotube dispersion liquid, the surfaceresistivity values were, respectively, 10^(8.3) and 10^(8.5) (Ω/sq), thetransmittance was excellent, and the dispersibility and coatability weregood, but the dispersion stability was bad. In addition, the scratchresistance was good for Comparative Example 3, and excellent forComparative Example 4.

These results indicate that the coating films manufactured in accordancewith the process of preparing the carbon nanotube dispersion liquidaccording to the present invention had excellent dispersibility,dispersion stability, coatability, surface resistivity, transmittance,and scratch resistance.

Experiment 2: Measurement of Characteristics of Conductive CoatingLiquid Composition and Antistatic Film Manufactured Therefrom

Example 12

A conductive coating liquid composition was produced by conducting aprocedure, five times, in which n-methyl pyrolidone (NMP) as a polarsolvent was added to a conductive coating liquid composition comprising83.3 wt % of a carbon nanotube dispersion liquid, 167.65 wt % of a TEOSsol binder, and 0.05 wt % of an additive then the mixture was allowed topass through a 100 μm nozzle under a pressure of 1,500 bar using ahigh-pressure disperser.

Example 13

A conductive coating liquid composition was produced under the samecondition as Example 12, except that dimethyl formamide (DMF) was addedas the polar solvent.

Comparative Example 5

A conductive coating liquid composition was produced under the samecondition as Example 12, except that no polar solvent was added.

In the above-described Examples 12 and 13, the conductive coating liquidcompositions were produced by varying the content of the polar solventto 1, 2, 3, 4, and 5 wt %, and then spin-coated on a substrate and curedfor 10 minutes at 140° C. Afterwards, the surface resistance of thecoating films was measured and tabulated in Table 4 below. In Table 4below, the surface resistance is denoted by the exponent X of 10^(X)Ω/sq.

TABLE 4 Surface Polar Solvent (wt %) Resistance NMP DMF (10^(×) Ω/sq)Comparative Example 5 0 0 8.8 Example 12 #1 1 0 7 #2 2 0 6.4 #3 3 0 5.5#4 4 0 4.9 #5 5 0 4.5 Example 13 #1 0 1 8.2 #2 0 2 7.5 #3 0 3 6.3 #4 0 45.6 #5 5 5.1

Referring to Table 4, the antistatic film made of the conductive coatingliquid composition comprising no polar solvent had a surface resistanceof 10^(8.8) Ω/sq. On the other hand, the surface resistance of theantistatic film made of the conductive coating liquid composition ofExample 12 comprising n-methyl pyrolidone as the polar solvent decreasedfrom 10⁷ Ω/sq to 10^(4.5) Ω/sq as the content of the polar solventincreased from 1 to 5. Also, the surface resistance of the antistaticfilm made of the conductive coating liquid composition of Example 13comprising dimethyl formamide as the polar solvent decreased from10^(8.2) Ω/sq to 10^(8.1) Ω/sq as the content of the polar solventincreased from 1 to 5.

These results indicate that an antistatic film made of a conductivecoating liquid composition comprising a polar solvent may have a lowersurface resistance than an antistatic film made of a conductive coatingliquid composition comprising no polar solvent. Also, these resultsindicate that the surface resistance of an antistatic film may beincreased or decreased to a desired level by adjusting the content ofthe polar solvent.

Accordingly, a conductive coating liquid composition according to thepresent invention can decrease and adjust the surface resistance of anantistatic film by comprising a polar solvent having a polarity of 10 orhigher.

As seen above, a conductive coating liquid composition according to thepresent invention can improve the surface resistance uniformity of anantistatic film and adjust its surface resistance by improving thedispersibility of carbon nanotubes by means of a polar solvent.

An antistatic film made of the conductive coating liquid compositionaccording to the present invention exhibits excellent electricalconductivity and excellent mechanical strength and transmittance, so itcan be used as an antistatic coating film for touchscreen panels anddisplay devices. An antistatic film and a display device comprising thesame can avoid failures caused by static electricity, preventdegradation in touch sensitivity, improve sheet resistance uniformity,thermal resistance, and reliability, and reduce manufacturing costs byeasily discharging static electricity generated during the manufacturingprocess.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the scope of the principles of thisdisclosure. More particularly, various variations and modifications arepossible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A conductive coating liquid compositioncomprising a carbon nanotube dispersion liquid comprising 0.05 to 20 wt% of carbon nanotubes, 0.02 to 40 wt % of a polyacrylic acid resin, 50to 99.93 wt % of a straight-chain alkanol having 2 to 5 carbon atoms,and 0.1 to 2 wt % of at least one additional dispersant, which is anacrylic block copolymer dispersant, based on 100 wt % of the carbonnanotube dispersion liquid; 10 to 100 parts by weight of a silane solbased on 100 parts by weight of the carbon nanotube dispersion liquid;and 0.1 to 5 wt % of a polar solvent based on 100 wt % of the conductivecoating liquid composition.
 2. The conductive coating liquid compositionof claim 1, wherein the polar solvent has a polarity of 10 or higher. 3.The conductive coating liquid composition of claim 2, wherein the polarsolvent comprises at least one selected from n-methyl pyrolidone (NMP),dimethyl sulphoxide (DMSO), and dimethyl formamide (DMF).
 4. Theconductive coating liquid composition of claim 1, wherein the silane solcomprises an alkoxysilane compound, an acid catalyst, an alcohol-basedsolvent, and water.
 5. The conductive coating liquid composition ofclaim 4, wherein the silane sol comprises 20 to 60 wt % of thealkoxysilane compound, 10 to 70 wt % of the alcohol-based solvent, and 5to 60 wt % of water based on the total weight of the silane sol.
 6. Adisplay device comprising an antistatic film comprising the conductivecoating liquid composition according to claim 1.